Preparation method of degradable PET composite material for blister packaging

Abstract

The invention relates to the technical field of PET polyester, and discloses a preparation method of a degradable PET composite material for blister packaging.The preparation method comprises the steps that 100 parts by weight of polyethylene glycol terephthalate and 1.2-4 parts by weight of polyester quaternary ammonium salt grafted chitosan are added into a double-screw extruder, melt extrusion and grain-sized dicing are conducted, and the degradable PET composite material for blister packagingis obtained. The chitosan is grafted with a polyethylene terephthalate-based polyester molecular chain, so that the compatibility between the chitosan and PET is better, and the influence on the mechanical property of the PET material is very small. Chitosan and grafted polyester molecular chains are also easy to biodegrade, so that the PET material has a relatively high biodegradation rate. A main chain of a chitosan-grafted polyester molecule contains a large number of quaternary ammonium salt antibacterial groups, and is matched with chitosan, so that the inhibiting and killing performance and the antibacterial rate of the PET material on escherichia coli and staphylococcus aureus are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of PET polyester, in particular to a method for preparing a degradable PET composite material for blister packaging. Background Art

[0002] Blister packaging products have the advantages of light weight and sealing performance, and can package any special-shaped products. At the same time, no additional cushioning materials are needed when packing. They are widely used in food packaging, medical drug transportation, electronic product protection, etc. The materials of blister packaging products are mainly polyvinyl chloride, polyethylene, polystyrene, polyethylene terephthalate, etc. Among them, polyethylene terephthalate PET has better heat resistance, high mechanical strength, and is biodegradable, with little green pollution, and is widely used.

[0003] Traditional PET materials do not have good antibacterial properties, which is not conducive to the practical application of PET in food, medical drug packaging, etc. Chitosan and its derivatives are a natural antibacterial agent with good biocompatibility, biodegradability, and green environmental protection, and have important applications in packaging materials. Adding chitosan to materials such as PET can improve the antibacterial and biodegradable properties of the material. Chinese patent CN111019171B discloses that modified aluminosilicate doped carboxylated chitosan is mixed with ethylene glycol to obtain a carboxylated chitosan / aluminosilicate / ethylene glycol blend, and then in-situ polymerized with terephthalic acid to obtain a PET modified masterbatch. The obtained PET protective film has good mechanical properties and water vapor barrier properties, but the PET protective film does not show excellent antibacterial properties. Usually, the antibacterial properties of the material are related to the amount of chitosan added. If the amount added is small, the antibacterial properties of the material are low. The present invention makes the PET material show higher antibacterial properties by adding a lower content of chitosan and its derivatives. Summary of the invention

[0004] The present invention solves the problem that the antibacterial performance of a degradable PET material for blister packaging is poor. The technical solution of the present invention: A method for preparing a degradable PET composite material for blister packaging:

[0005] (1) Add dimethyl sulfoxide, carboxymethyl chitosan, bromohydrin, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide to a reaction vessel, stir and react at 20-30° C. for 7-12 hours, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain bromocarboxylate chitosan. The reaction formula is:

[0006]

[0007] (2) Add N,N-dimethylformamide, bromocarboxylate chitosan, N,N,N',N'-tetramethylethylenediamine, and bromophthalate into a reaction vessel, stir and react at 100-120° C. for 36-48 hours, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain polyester quaternary ammonium salt grafted chitosan. The reaction formula is:

[0008]

[0009] (3) 100 parts by weight of polyethylene terephthalate and 1.2-4 parts by weight of polyester quaternary ammonium salt grafted chitosan are added into a twin-screw extruder, the temperatures of each section are 220° C., 255° C., 265° C., 265° C., and 260° C., the screw speed is 30-50 r / min, and melt extrusion and pelletization are performed to obtain a degradable PET composite material for blister packaging.

[0010] Preferably, in (1), the amount of carboxymethyl chitosan is 100 parts by weight, the amount of bromohydrin is 2-6 parts by weight, the amount of 4-dimethylaminopyridine is 0.9-3.1 parts by weight, and the amount of N,N-dicyclohexylcarbodiimide is 3.3-10.8 parts by weight, wherein the bromohydrin is 2-bromoethanol, 3-bromopropanol or 4-bromobutanol.

[0011] Preferably, in (2), the amount of brominated carboxylate chitosan is 100 parts by weight, the amount of N,N,N',N'-tetramethylethylenediamine is 12-30 parts by weight, and the amount of brominated phthalate is 40-126 parts by weight.

[0012] Preferably, the preparation method of brominated phthalates is as follows: in an ice bath, dichloromethane, 100 parts by weight of terephthaloyl chloride, 250-306 parts by weight of bromohydrin, and 190-220 parts by weight of triethylamine are added to a reaction vessel, and then reacted at 20-25° C. for 18-24 hours, extracted and washed with a 5% potassium carbonate solution by mass, and after separation, anhydrous sodium sulfate is added to the dichloromethane organic phase, dried to remove water, filtered, and the filtrate is rotary evaporated, and the product is recrystallized in ethyl acetate to obtain brominated phthalates. The bromohydrin is 2-bromoethanol, 3-bromopropanol or 4-bromobutanol. The reaction formula is:

[0013]

[0014] The beneficial technical effect of the present invention is as follows: bromoalcohols such as 2-bromoethanol are used to carry out esterification reaction with carboxymethyl chitosan to obtain brominated carboxylate chitosan, and bromine atoms are used as polymerization sites to carry out quaternization graft polymerization reaction with N,N,N',N'-tetramethylethylenediamine and brominated phthalate to obtain polyester quaternary ammonium salt grafted chitosan, thereby introducing polyester molecular chains containing terephthalate structural units and quaternary ammonium salts into the side chains of chitosan.

[0015] The invention melt-mixes polyethylene terephthalate and polyester quaternary ammonium salt grafted chitosan to obtain a degradable PET composite material for blister packaging. Chitosan is grafted with a terephthalate-based polyester molecular chain similar to PET, so that the compatibility between chitosan and PET is better, the mechanical properties of the PET material are slightly affected, and the PET material still maintains a high impact strength.

[0016] The chitosan of the invention has excellent biodegradability, and the grafted polyester molecular chain is also very easy to biodegrade, so that the PET material has a high biodegradability. In addition, the main chain of the polyester molecular grafted with chitosan contains a large amount of quaternary ammonium salt antibacterial groups, which are matched with chitosan, and the addition amount is only 1.5-4%, which significantly improves the inhibition and killing performance and antibacterial rate of the PET material on Escherichia coli and Staphylococcus aureus, and shows stronger antibacterial performance. The prepared PET material has good practical applications in blister packaging products, food packaging, medical product packaging, etc. DETAILED DESCRIPTION

[0017] Although the above describes the specific implementation scheme of the present invention, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical scheme of the present invention without creative work are still within the scope of protection of the present invention.

[0018] The following carboxymethyl chitosan, with an active ingredient content of 99%, was purchased from Xi'an Tianzheng Pharmaceutical Excipients Co., Ltd. Chitosan quaternary ammonium salt, with an active ingredient content of 99%, was purchased from Xi'an Tianzheng Pharmaceutical Excipients Co., Ltd. Polyethylene terephthalate PET was purchased from Shenzhen Wansuyuan Rubber & Plastic Co., Ltd.

[0019] Example 1

[0020] (1) Add 100 mL of dichloromethane, 20 g of terephthaloyl chloride, 50 g of 2-bromoethanol, and 40 g of triethylamine to a reaction vessel, and then react at 20° C. for 24 hours, extract and wash with a 5% by mass potassium carbonate solution, and after separation, add anhydrous sodium sulfate to the dichloromethane organic phase, dry and remove water, filter, and rotary evaporate the filtrate. The product is recrystallized in ethyl acetate to obtain brominated phthalate. The structural formula is:

[0021]

[0022] (2) 4 L of dimethyl sulfoxide, 200 g of carboxymethyl chitosan, 4 g of 2-bromoethanol, 1.8 g of 4-dimethylaminopyridine, and 6.6 g of N,N-dicyclohexylcarbodiimide were added to a reaction container, and the mixture was stirred at 25° C. for 7 h. Ethanol was added to the solution to precipitate the precipitate, which was filtered, washed with ethanol, and dried to obtain bromocarboxylate chitosan.

[0023] (3) Add 2L N,N-dimethylformamide, 100g bromocarboxylate chitosan, 12g N,N,N',N'-tetramethylethylenediamine, and 40g bromophthalate into a reaction container, stir and react at 120°C for 36h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain polyester quaternary ammonium salt grafted chitosan.

[0024] (4) 10 kg of polyethylene terephthalate and 120 g of polyester quaternary ammonium salt grafted chitosan were added into a twin-screw extruder. The temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C. The screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0025] Example 2

[0026] (1) Add 120 mL of dichloromethane, 20 g of terephthaloyl chloride, 61.2 g of 4-bromobutanol, and 44 g of triethylamine to a reaction vessel, and then react at 20° C. for 24 hours, extract and wash with a 5% by mass potassium carbonate solution, and after separation, add anhydrous sodium sulfate to the dichloromethane organic phase, dry and remove water, filter, and rotary evaporate the filtrate. The product is recrystallized in ethyl acetate to obtain brominated phthalate. The structural formula is:

[0027] (2) Add 5 L of dimethyl sulfoxide, 200 g of carboxymethyl chitosan, 8 g of 4-bromobutanol, 4.2 g of 4-dimethylaminopyridine, and 14.3 g of N,N-dicyclohexylcarbodiimide into a reaction container, stir and react at 20° C. for 12 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain bromocarboxylate chitosan.

[0028] (3) Add 2.5 L N,N-dimethylformamide, 100 g bromocarboxylate chitosan, 20 g N,N,N',N'-tetramethylethylenediamine, and 85 g bromophthalate into a reaction container, stir and react at 100° C. for 48 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain polyester quaternary ammonium salt grafted chitosan.

[0029] (4) 10 kg of polyethylene terephthalate and 250 g of polyester quaternary ammonium salt grafted chitosan were added into a twin-screw extruder. The temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C. The screw speed was 30 r / min. The mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0030] Example 3

[0031] (1) Add 120 mL of dichloromethane, 20 g of terephthaloyl chloride, 55.8 g of 3-bromopropanol, and 38 g of triethylamine to a reaction vessel, and then react at 25° C. for 18 h. Extract and wash with a 5% potassium carbonate solution. After separation, add anhydrous sodium sulfate to the dichloromethane organic phase, dry and remove water, filter, and rotary evaporate the filtrate. The product is recrystallized in ethyl acetate to obtain brominated phthalates. The structural formula is

[0032] (2) Add 5 L of dimethyl sulfoxide, 200 g of carboxymethyl chitosan, 12 g of 3-bromopropanol, 6.2 g of 4-dimethylaminopyridine, and 21.6 g of N,N-dicyclohexylcarbodiimide into a reaction container, stir and react at 30° C. for 10 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain bromocarboxylate chitosan.

[0033] (3) Add 3 L of N,N-dimethylformamide, 100 g of bromocarboxylate chitosan, 30 g of N,N,N',N'-tetramethylethylenediamine, and 126 g of bromophthalate into a reaction container, stir and react at 110° C. for 48 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain polyester quaternary ammonium salt grafted chitosan.

[0034] (4) 10 kg of polyethylene terephthalate and 400 g of polyester quaternary ammonium salt grafted chitosan were added into a twin-screw extruder. The temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C. The screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0035] Comparative Example 1

[0036] (1) 10 kg of polyethylene terephthalate was added into a twin-screw extruder, the temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C., the screw speed was 50 r / min, and the mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0037] Comparative Example 2

[0038] (1) 10 kg of polyethylene terephthalate and 120 g of carboxymethyl chitosan were added into a twin-screw extruder, the temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C., the screw speed was 50 r / min, and the mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0039] Comparative Example 3

[0040] (1) 10 kg of polyethylene terephthalate and 120 g of chitosan quaternary ammonium salt are added to a twin-screw extruder, the temperatures of each section are 220° C., 255° C., 265° C., 265° C., and 260° C., the screw speed is 50 r / min, and the mixture is melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0041] Comparative Example 4

[0042] (1) Add 2 L of N,N-dimethylformamide, 100 g of bromocarboxylate chitosan, 12 g of N,N,N',N'-tetramethylethylenediamine, and 19.8 g of 1,2-dibromoethane into a reaction container, stir and react at 120° C. for 36 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain polymerized quaternary ammonium salt grafted chitosan.

[0043] (2) 10 kg of polyethylene terephthalate and 120 g of polymerized quaternary ammonium salt grafted chitosan were added into a twin-screw extruder. The temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C. The screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0044] Comparative Example 5

[0045] (1) Add 2 L of N,N-dimethylformamide, 100 g of carboxymethyl chitosan, 12 g of N,N,N',N'-tetramethylethylenediamine, and 40 g of bromophthalate into a reaction container, stir and react at 120° C. for 36 h, add ethanol to the solution to precipitate, filter, wash with ethanol, and dry to obtain a polyester quaternary ammonium salt-chitosan mixture.

[0046] (2) 10 kg of polyethylene terephthalate and 120 g of a polyester quaternary ammonium salt-chitosan mixture were added to a twin-screw extruder. The temperatures of each section were 220° C., 255° C., 265° C., 265° C., and 260° C. The screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain a biodegradable PET composite material for blister packaging.

[0047] The PET composite material was made into a specimen by an injection molding machine at an injection molding temperature of 265°C. The cantilever beam impact strength was tested according to the national standard GB / T1843-2008. The biodegradability was tested according to the standard GB / T 19277.2-2013.

[0048] The antibacterial performance was tested according to the method of QB / T2591-2003. The test bacteria were Escherichia coli and Staphylococcus aureus. The antibacterial rate R = (BC) / B × 100%. B is the average number of recovered bacteria (cfu / piece) of the blank control sample (Comparative Example 1). C is the average number of recovered bacteria (cfu / piece) of the antibacterial plastic sample.

[0049] Table 1 PET composite material performance test

[0050]

[0051] As shown in Table 1, compared with the PET material in Comparative Example 1, polyester quaternary ammonium salt grafted chitosan was added in Examples 1-3, and chitosan was grafted with terephthalate groups similar to PET. The polyester molecular chain makes the compatibility between chitosan and PET better, and has little effect on the mechanical properties of the material. The PET material still maintains a high impact strength, and chitosan has excellent biodegradability. At the same time, the grafted polyester molecular chain is also easily biodegradable, making the PET material have a high biodegradation rate. At the same time, the main chain of the polyester molecular grafted with chitosan contains a large number of quaternary ammonium salt antibacterial groups. When combined with chitosan, the addition amount is only 1.5-4%, which significantly improves the inhibition and killing performance and antibacterial rate of PET materials on Escherichia coli and Staphylococcus aureus, showing stronger antibacterial properties.

[0052] The PET material of Comparative Example 2 is added with only carboxymethyl chitosan, which does not contain quaternary ammonium salt groups and has poor compatibility with PET, which will affect the mechanical properties of the material and cause a significant decrease in impact strength.

[0053] In Comparative Example 3, conventional chitosan quaternary ammonium salt is added, which has poor compatibility with PET and will affect the mechanical properties of the material, resulting in a significant decrease in impact strength.

[0054] Comparative Example 4 uses N,N,N',N'-tetramethylethylenediamine and 1,2-dibromoethane (without ester group) as raw materials to prepare polymerized quaternary ammonium salt grafted chitosan, which does not contain polyester molecular chains, has poor compatibility with PET, and the impact strength of the material decreases significantly. In addition, the polymerized quaternary ammonium salt does not contain degradable polyester molecular chains, which will reduce the biodegradation rate of the material. However, the main chain of the polymerized quaternary ammonium salt grafted with chitosan contains a large number of quaternary ammonium salt antibacterial groups, which, in combination with chitosan, significantly improves the antibacterial rate of PET materials against Escherichia coli and Staphylococcus aureus.

[0055] The carboxymethyl chitosan in Comparative Example 5 does not contain bromine atoms and cannot undergo graft polymerization reaction with N,N,N',N'-tetramethylethylenediamine and brominated phthalate, resulting in no grafted polyester molecular chain on chitosan. The compatibility of chitosan with PET is poor, and the impact strength of the material decreases significantly.

Claims

1. A method for preparing a degradable PET composite material for blister packaging, characterized in that: The preparation method is as follows: (1) adding dimethyl sulfoxide, carboxymethyl chitosan, bromohydrin, 4-dimethylaminopyridine and N,N-dicyclohexylcarbodiimide into a reaction container, stirring for reaction, adding ethanol to the solution to precipitate a precipitate, filtering, washing and drying to obtain bromocarboxylate chitosan; (2) adding N,N-dimethylformamide, bromocarboxylate chitosan, N,N,N',N'-tetramethylethylenediamine, and bromophthalate into a reaction container, stirring to react, adding ethanol to the solution to precipitate the precipitate, filtering, washing, and drying to obtain polyester quaternary ammonium salt grafted chitosan; The structural formula of the brominated phthalate is The R group is -CH2CH2-, -CH2CH2CH2- or -CH2CH2CH2CH2-; (3) 100 parts by weight of polyethylene terephthalate and 1.2-4 parts by weight of polyester quaternary ammonium salt grafted chitosan are added into a twin-screw extruder, melt-extruded, and pelletized to obtain a degradable PET composite material for blister packaging.

2. The method for preparing the degradable PET composite material for blister packaging according to claim 1, characterized in that: The reaction temperature in (1) is 20-30°C and the reaction time is 7-12h.

3. The method for preparing the degradable PET composite material for blister packaging according to claim 1, characterized in that: In the above (1), the amount of carboxymethyl chitosan is 100 parts by weight, the amount of bromohydrin is 2-6 parts by weight, the amount of 4-dimethylaminopyridine is 0.9-3.1 parts by weight, and the amount of N,N-dicyclohexylcarbodiimide is 3.3-10.8 parts by weight.

4. The method for preparing the degradable PET composite material for blister packaging according to claim 1, characterized in that: The reaction temperature in (2) is 100-120°C, and the reaction time is 36-48h.

5. The method for preparing the degradable PET composite material for blister packaging according to claim 1, characterized in that: In the above (2), the amount of brominated carboxylate chitosan is 100 parts by weight, the amount of N,N,N',N'-tetramethylethylenediamine is 12-30 parts by weight, and the amount of brominated phthalate is 40-126 parts by weight.

6. The method for preparing the degradable PET composite material for blister packaging according to claim 1, characterized in that: The preparation method of the brominated phthalate is as follows: in an ice bath, dichloromethane, 100 parts by weight of terephthaloyl chloride, 250-306 parts by weight of bromohydrin, and 190-220 parts by weight of triethylamine are added to a reaction container, and then reacted at 20-25° C. for 18-24 hours, extracted and washed with a potassium carbonate solution, and the extracted product is recrystallized to obtain the brominated phthalate.

7. The method for preparing the degradable PET composite material for blister packaging according to claim 3 or 6, characterized in that: The bromoalcohol is 2-bromoethanol, 3-bromopropanol or 4-bromobutanol.

8. The method for preparing a degradable PET composite material for blister packaging according to claim 1, characterized in that: The temperature of each section of the twin-screw extruder in (3) is 220-265°C, and the screw speed is 30-50r / min.

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